1. Field of the Invention
This invention relates generally to printing presses, to web-fed printing presses, and to improvements in the construction of a folding station customarily appended to a web-fed printing press for cutting and folding the printed web into multiple-page signatures. More particularly, the invention deals with a perforator incorporated in the folding station for creating a series of incisions longitudinally and medially of the web description of the Prior Art, in order to expedite the subsequent folding of the web.
2. Description of the Prior Art
The art of longitudinally perforating the printed web of paper, and folding the same along the series of perforations, at the folding station (shown in FIG. 1 of the drawings attached hereto) of the rotary printing press has been known and practiced extensively. Japanese Patent No. 3,034,702 represents a typical prior art device directed to the art, teaching use of a pair of cylinders placed opposite each other via the web. One of the cylinders carries a perforating tool, a sawtooth-edged perforating blade of annular shape arranged circumferentially thereon, and the other a bed or anvil with a groove therein to receive the sawtooth edge of the perforating blade via the web. The opposed pair of the blade cylinder and anvil cylinder are positioned between a former, by which the printed web is doubled along its longitudinal centerline, and an opposed pair of a folding cylinder and jaw cylinder by which the doubled web is cut transversely and again folded into eight-page signatures.
This prior art device is objectionable, among other reasons, for its large space requirement. Placed as above between the former and the folding and jaw cylinders, the blade cylinder and anvil cylinder make the folding station, and therefore the complete printing press system, inordinately bulky.
This drawback is absent from Japanese Unexamined Patent Publication No. 10-114,048, which suggests use of one blade cylinder and one anvil cylinder for both transversely and longitudinally perforating the web. The singular blade cylinder carries on its surface both a transversely perforating blade, which extends linearly along the cylinder axis, and a longitudinally perforating blade of annular shape extending circumferentially. The singular anvil cylinder has formed on its surface both an anvil of linear shape for the transversely perforating blade, and another anvil of annular shape for the longitudinally perforating blade. The web is therefore perforated both transversely and longitudinally as it passes between these dual blade cylinder and dual anvil cylinder.
Although so simple and compact in construction, this second prior art device has a serious inconvenience arising from the fact that not all the printings are necessarily perforated longitudinally besides being perforated transversely. The longitudinally perforating blade must therefore be detached from the blade cylinder when the web needs only transverse perforation, and remounted when it needs both transverse and longitudinal perforations.
Japanese Patent No. 3,166,087 utilizes preexisting feed roller means which lie between the noted former and the noted pair of folding cylinder and jaw cylinder in order to feed the web into and through the folding station. The feed roller means include one feed roller and, held against this feed roller, a pair of nip rollers of smaller size which are mounted on a common shaft with an axial spacing therebetween. A longitudinally perforating blade is mounted on the nip roller shaft, and an associated anvil on the drive roller.
An objection to this patent concerns the fact that the nip roller pair together with their supporting shaft are jointly movable toward and away from the drive roller in order to adjust to the variable thickness of the web traveling therebetween. As a result, according to this prior art device, the longitudinally perforating blade on the nip roller shaft incised the web to a variable depth depending upon the thickness of the web, sometimes failing to create perforations of sufficient size for the web to be subsequently folded correctly.